Ordinarily, as fuels in combustion appliances, such as lighters for smoker's requisites, other types of lighters, torches, and illumination devices, alcohol fuels, such as ethyl alcohol, petroleum benzine types of benzine fuels, or liquefied gas fuels, such as butane gas or propane gas, have heretofore been utilized.
The performances, the levels of convenience of handling, and the design structures of the combustion appliances vary in accordance with the kinds of the fuels used, and the fuels have their own features.
For example, in cases where the benzine fuels, which are mixtures of petroleum benzine types of hydrocarbon compounds, are used, since such a fuel is the mixture of the compounds having different boiling points, the problems described below occur. Specifically, a benzine constituent having a low boiling point volatilizes at the initial stage of use, at which the combustion appliance is lighted, and the constituent which volatilizes successively shifts to hydrocarbons having high boiling points. Therefore, the composition of the fuel, which remains in the combustion appliance, changes with the passage of the combustion time, and a change in flame length occurs. The same problems are also encountered with gasoline. Also, since benzine has a high volatility, the combustion appliance using benzine must have an enclosed structure for reducing the volatilization of benzine from a fuel storage region and the portion of a combustion wick. If the enclosure is insufficient, the fuel will be lost due to volatilization, and the operation for replenishing the fuel must be carried out very frequently. Further, benzine and gasoline have specific odors, which some persons dislike.
The liquefied gas fuels have a high gas pressure at temperatures falling within the range, in which the combustion appliance is used, and therefore the vessel for storing the fuels must have a pressure-resistant structure. Also, the flame length varies in accordance with variations in gas pressure. In particular, the liquefied gas fuels have the characteristics such that their gas pressures markedly vary logarithmically with respect to temperatures, and therefore the problems occur in that the flame length changes markedly, depending upon temperatures. In order for the change in flame length to be reduced, a special design countermeasure for carrying out temperature compensation for a fuel feeding mechanism of the combustion appliance must be taken. Therefore, the structure cannot be kept simple, and the cost cannot be kept low.
As for the alcohol fuels, lower monohydric alcohols, such as ethyl alcohol, methyl alcohol, and propyl alcohol, are liquids at normal temperatures and have comparatively low vapor pressures. Therefore, the enclosure with respect to the fuel storing region and the combustion wick may be carried out with a comparatively simple enclosed structure such that the alcohols may not volatilize. Accordingly, the structure of the combustion appliance can be kept simple, and the cost can be kept comparatively low. However, the alcohol fuels have the problems in that their combustion flames are colorless and cannot easily be perceived visually, and therefore the lighting and burning state cannot be confirmed easily at a light site.
Various techniques for coloring the flames produced by the alcohol fuels described above have heretofore been proposed. In a first technique, a flame reaction coloring agent is blown into the combustion flame, and the combustion flame is colored with the flame reaction. However, it is difficult for the first technique to be employed for small combustion appliances, such as lighters.
In a second technique, a flame reaction coloring agent is dissolved in the alcohol fuels. As such a flame reaction coloring agent, a metal salt, which is capable of undergoing a flame reaction and soluble in alcohols, is used. Examples of the flame reaction agents using the metal salts include cupric oxide, strontium chloride, potassium carbonate, lithium nitrate, lithium chloride, boric acid esters, lithium bromide, and cesium carbonate. (Such agents are disclosed in, for example, Japanese Unexamined Patent Publication Nos. 59(1984)-155480 and 61(1986)-222981, Japanese Unexamined Utility Model Publication Nos. 1(1989)-101071and2(1990)-147657, and Japanese Unexamined Patent Publication Nos. 4(1992)-117493 and4(1992)-65488.)
However, with the combustion appliances using the liquid fuels, which contain the aforesaid metal salts added as the flame reaction agents to alcohols, the problems described below occur. Specifically, in the structure, in which the liquid fuel is sucked up with the capillarity through the combustion wick and is lighted at the end portion of the combustion wick, as the combustion of the liquid fuel proceeds, the flame reaction agent is successively sucked up together with the alcohol fuel and is deposited on the surface of the combustion wick. As a result, the combustion wick is clogged with the deposited metal salt. Due to the clogging of the combustion wick, the suction of the fuel through the combustion wick is obstructed, the flame length becomes short, and a lighting failure occurs ultimately.
In the present invention, research has been carried out to obtain a flame reaction agent, which is free from the occurrence of the clogging of the combustion wick due to the addition of the flame reaction agent described above. The present invention eliminates the problems with regard to the colorless flame produced by the combustion of alcohols, and enhances the convenience of the use of alcohol types of liquid fuels.
Specifically, in view of the advantages of a combustion appliance using an alcohol fuel containing an alcohol, such as a lower monohydric alcohol, as the principal constituent, in that the structure can be kept simple without the necessity of the consideration of the volatility of benzine in a combustion appliance using petroleum benzine types of mixed hydrocarbon compounds and the consideration of a high-pressure gas in a combustion appliance using a liquefied gas fuel, the object of the present invention is to provide a liquid fuel for combustion appliances, which has good characteristics, such as stabilization of the flame length of a combustion flame, which enables the combustion flame to be colored efficiently by the selection of a flame reaction agent that does not adversely affect the good characteristics, and which thereby enables the lighting and burning state to be easily perceived visually. Another object of the present invention is to provide a combustion appliance, such as a lighter for smoker's requisites, in which the liquid fuel is used.
Also, in the present invention, research has been carried out to develop a liquid fuel, which provides convenience of a level equivalent to that of the alcohol type of liquid fuel described above, and which eliminates the problems with regard to a colorless flame produced by combustion.
Specifically, a further object of the present invention is to provide a liquid fuel for combustion appliances, which has good characteristics equivalent to those of an alcohol fuel, such as stabilization of the flame length of a combustion flame, which produces a colored combustion flame, and which has no hygroscopic property. A still further object of the present invention is to provide a combustion appliance, such as a lighter for smoker's requisites, in which the liquid fuel is used.